Spec

Free guide · iPhone and Android

Why is my mobile data draining so fast?

Plain answers to what people ask most when their mobile data disappears, with the steps to fix it.

The five-minute fix

  1. Find the app: Settings, then Cellular (iPhone) or App data usage (Android).
  2. Turn on Low Data Mode (iPhone) or Data Saver (Android).
  3. Set app updates, backups and photo uploads to Wi-Fi only.
  4. Turn off Wi-Fi Assist, or Switch to mobile data, so a weak Wi-Fi doesn’t use your data.
  5. Set a data warning below your allowance.

Menu names change between phone makers and versions. If you can’t find one, type its name into the search box at the top of Settings. Updated 28 September 2026.

On this page

Where did my data go?

Make your data last and pay less

Tracking and data your phone sends

Where did my data go?

Why is my mobile data draining so fast?

Usually video. Videos that play by themselves in social apps, streaming in high quality, and photos or backups uploading to the cloud use far more data than messages or web pages. Your phone lists which apps used the most, so start there.

iPhone

  1. Open Settings, then Cellular (called Mobile Service or Mobile Data in some countries).
  2. Scroll down: each app is listed with the data it has used.
  3. Turn the switch off for any app that doesn’t need mobile data.

Android

  1. Open Settings, then Network & internet, then SIMs (or Internet), and tap your SIM.
  2. Tap App data usage to see which apps used the most.
  3. On Samsung phones: Settings, then Connections, then Data usage, then Mobile data usage.

Why is my data gone overnight?

Your phone kept working while you slept. The usual causes are backups and photo uploads, app and system updates, and apps refreshing in the background. If your Wi-Fi dropped in the night, all of that ran on mobile data instead.

iPhone

  1. Settings, then General, then Background App Refresh: choose Wi-Fi, or Off.
  2. Settings, then App Store: turn off Automatic Downloads under Cellular Data.
  3. Settings, then your name, then iCloud, then iCloud Backup: turn off Back Up Over Cellular, if you see it.

Android

  1. Play Store, then your profile picture, then Settings, then Network preferences: set Auto-update apps to Over Wi-Fi only.
  2. Settings, then Apps, then the app, then Mobile data & Wi-Fi: turn off Background data.

What app is using all my background data?

Your phone’s own data list shows every app’s use. Android also splits it into foreground (while you use the app) and background (while you don’t).

iPhone

  1. Settings, then Cellular: the list shows each app’s total.
  2. iPhone doesn’t split out background use. Turn off Background App Refresh for the apps near the top and see if it drops.

Android

  1. In App data usage, tap an app: it shows Foreground and Background separately.
  2. Turn off Background data for apps with a lot of background use.

On iPhone the totals count from the last time they were reset, which may be years ago, not this month. Tap Reset Statistics at the bottom of the Cellular page on the day your plan renews, and you will see one month at a time.

Why is my phone using data when I’m on Wi-Fi?

Your phone switches to mobile data when the Wi-Fi is weak, or connected but not reaching the internet, so things keep loading. Turn that off if you would rather they wait for Wi-Fi.

iPhone

  1. Settings, then Cellular: scroll to the bottom and turn off Wi-Fi Assist.

Android

  1. Samsung: Settings, then Connections, then Wi-Fi, then the ⋮ menu, then Intelligent Wi-Fi: turn off Switch to mobile data.
  2. Other phones: look in the Wi-Fi settings for a similar option, or search Settings for “mobile data”.

A Wi-Fi network that asks you to sign in on a web page, as in hotels and cafés, doesn’t reach the internet until you do.

Are hidden apps using my mobile data?

Apps can’t hide from the phone’s own data list, so look there for anything you don’t recognise. It also shows the phone’s own use and your hotspot: everything a laptop or tablet uses through your hotspot counts against your data too. Delete apps you no longer use, because they can still update and refresh in the background.

iPhone

  1. Settings, then Cellular: check System Services and Personal Hotspot in the list.

Android

  1. In App data usage, check the Android system entries, Removed apps, and Hotspot or Tethering.

Make your data last and pay less

How do I stop my mobile data from running out?

Turn on your phone’s data saving mode, set video to a lower quality in the apps you watch most, and download music, maps and shows on Wi-Fi before you go out. Set a warning so you know before you run out.

iPhone

  1. Settings, then Cellular, then Cellular Data Options: turn on Low Data Mode (on some iPhones it’s under Data Mode).

Android

  1. Settings, then Network & internet, then Data Saver: turn it on.
  2. Settings, then Network & internet, then SIMs, then your SIM, then Data warning & limit: set a warning below your allowance.

Most video and social apps have their own setting, often called data saver or video quality on mobile data. It makes the biggest difference.

How can I lower my mobile data bill?

First find out how much you really use. Your carrier’s app or bill shows the last few months. If you use less than you pay for, ask for a smaller plan. If you keep running out, a bigger plan can cost less than buying extra data each month. If your contract has ended, ask about a SIM-only plan: you keep your phone and pay only for the service.

How do I save mobile data on a family plan?

Many carriers let the account holder see each line’s use, and set a limit per line, in their app or online account. Ask yours if you can’t find it. Then turn on data saving on each phone and set updates and backups to Wi-Fi only, using the steps above.

Why is mobile data so expensive per gigabyte?

Carriers pay to build and run masts, and for licences to use the radio frequencies. Prices also depend on how many carriers compete where you live, so the price per gigabyte differs a lot between countries and between plans. To compare plans, divide the monthly price by the gigabytes included.

Tracking and data your phone sends

How do I stop apps tracking me and showing ads?

You can’t switch it all off, but you can cut it down: stop apps using your advertising ID, remove apps you don’t use, and choose which apps can see your location.

iPhone

  1. Settings, then Privacy & Security, then Tracking: turn off Allow Apps to Request to Track.
  2. Settings, then Privacy & Security, then Apple Advertising: turn off Personalized Ads.
  3. Settings, then Privacy & Security, then Location Services: set apps to While Using or Never.

Android

  1. Settings, then Privacy (or Security & privacy, then More privacy settings), then Ads: tap Delete advertising ID.
  2. Settings, then Location, then App location permissions: set apps to Allow only while using the app, or Don’t allow.

How do I block background telemetry from apps?

Telemetry is the usage and crash reports that apps and the phone send home. Turn off the phone’s own sharing in its settings. For other apps, stopping their background data stops them sending while you aren’t using them.

iPhone

  1. Settings, then Privacy & Security, then Analytics & Improvements: turn off Share iPhone Analytics.
  2. Turn off Background App Refresh for apps that don’t need it.

Android

  1. Search Settings for “Usage & diagnostics” and turn it off.
  2. Turn off Background data for apps that don’t need it.

A private DNS service with a blocklist can block many known tracking addresses for every app at once. On Android it’s under Settings, then Network & internet, then Private DNS. Choose a provider you trust: it sees the names of the sites your phone looks up.

Why do apps use data when they’re closed?

Closing an app doesn’t always stop it. Apps are allowed to receive notifications, refresh their content, upload photos and download updates in the background. The background settings control this: Background App Refresh on iPhone, and Background data or Data Saver on Android.

How do I stop my phone sending data to cloud servers?

Most of it is backup and sync you turned on when you set the phone up: photos, contacts, messages and files. Choose what syncs, and make it wait for Wi-Fi.

iPhone

  1. Settings, then your name, then iCloud: turn off what you don’t want stored there.
  2. Settings, then Photos, then Cellular Data: turn it off so photos upload on Wi-Fi only.
  3. Settings, then Cellular: turn off iCloud Drive at the bottom of the list.

Android

  1. Google Photos, then your profile picture, then Photos settings, then Backup: turn off backing up over mobile data.
  2. Settings, then Google, then Backup: choose what is backed up.

Keep your photos backed up on Wi-Fi at least: if the phone is lost, the backup is the only copy.

From Spec. This guide is free, with no sign-up, no ads and no tracking.